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Eukaryogenesis, the process which created the eukaryotic cell and lineage, is a milestone in the evolution of life, since eukaryotes include all complex cells and almost all multicellular organisms. The process is widely agreed to have involved symbiogenesis , in which an archeon and a bacterium came together to create the first eukaryotic ...
In any case, the problem lay buried in the catch-all rubric "origin of life"--where, because it is a biological not a (bio)chemical problem, it was effectively ignored. Scientific interest in cellular evolution started to pick up once the universal phylogenetic tree, the framework within which the problem had to be addressed, was determined.
The era saw the development of sexual reproduction, which greatly increased the complexity of life to come and signified the start of development of true multicellular organisms. [6] [13] Though the biota of the era was once thought to be exclusively microbial, recent finds have shown multicellular life did exist during the Mesoproterozoic.
In biology, evolution is any change across successive generations in the heritable characteristics of biological populations. Evolutionary processes give rise to diversity at every level of biological organization , from kingdoms to species , and individual organisms and molecules , such as DNA and proteins .
The history of life on Earth traces the processes by which living and extinct organisms evolved, from the earliest emergence of life to the present day. Earth formed about 4.5 billion years ago (abbreviated as Ga, for gigaannum) and evidence suggests that life emerged prior to 3.7 Ga. [1] [2] [3] The similarities among all known present-day species indicate that they have diverged through the ...
Multicellular life is made possible by the coordination of physically and temporally distinct processes, most prominently through hormones.Hormones mediate critical activities in vertebrates, including ontogeny, somatic and reproductive physiology, sexual development, performance and behaviour.
A multicellular organism is an organism that consists of more than one cell, unlike unicellular organisms. [1] All species of animals, land plants and most fungi are multicellular, as are many algae, whereas a few organisms are partially uni- and partially multicellular, like slime molds and social amoebae such as the genus Dictyostelium. [2] [3]
In the second half of the 20th century, a number of fossil forms have been found in Proterozoic rocks, particularly in ones from the Ediacaran, proving that multicellular life had already become widespread tens of millions of years before the Cambrian Explosion in what is known as the Avalon Explosion. [27]